Fluid pressure control apparatus



Feb. 6, 1951 R. J. BUSH 2,540,710

' FLUID PREssuREcoNTRoL APPARATUS Filed Aug. 21. 1947 2 sheets-sheet 1 Pi IoTs omL rol Engneers CornL rol mllh r'oHle RanKnIJBUSh @wd l ATToRzwY Patented Feb. '6, 1951 UNITED STATES PATENT OFFICE FLUID` PRESSURE CONTROL APPARATUS `Rankin J. Bush, Greensburg, Pa., assignor to The VWestinghouse'Air Brake Company, Wilme'ding, Pa., 'a corporation of Pennsylvania Application August 21, 1947,. Serial No..7679,845

tween the stations.` It is further desirable that the 'engineer'be able to remove yfrom the pilots controler-an engine in case ofV emergency such asfaulty operation thereof and restore the controltov the .pilot'upon repair ofthe engine. 'It is further desirable incase of accidental reduction in pressure of controlling fluid that the .engine speed be maintained sunlci'ent to insure safe operation of the plane.

The yprincipal object of the present invention is the provision of an improved fluid pressure control apparatus for accomplishing the above results.V

` Other objectsand advantages will be apparent from'the following more detailed description of the invention.

In the accompanying drawings; Figs. .1,. l-A, when `the lefthand end of Fig'. 1 is matchedto the right hand end ,of.Fig. l.-A, isa diagrammatic yView of a llluid y.pressure control system embodying onefform of vt'heinvention; Fig. 2 is a diagrammatic rear View of an operating lever mechanism and lockout lever arrangement shown in Fig. 1--A; portions `of the mechanism being brokenaway for the sake of clarity; Fig. 3 is a diagrammatic cut-away View of a selector valve device operating handle mechanism as viewed in the `direction of. arrow 3, iniFig. 1-`A, and Figa is a diagrammatic development of connections effected -in three positions of saidselector valve device.

In` actual practice the improved iiuid pressure control apparatus is adapted to provide syn- .chronouscontrol of a plurality of engines .or other Adevices from a vsingle operators control device at. one. control station and individual control .ol said engines or devices by individual operators control devices at another station, vsuch `as,.re .spectivelyppilots and engineers control stations 'inail airplane. Forthe purpose of simplicityin illustrating-` the .invention howevenwhich will be vS'fClaims. (Cl. 121438) 2 presently described,thereY is shown inthe draw" ing, only Yoneengine control device, Land two Voperators control devices therefore, intended to be located at different control stations. v

As shownin Figs. 1 and l-A, reference numeral I designates a uid pressure motor adapt'- ed to position a device such as an aircraft engine throttle between idle and'full speed positions in accordance with variations in pressure of'iiuid supplied to said motorbetween a minimum vpressure of say eighty (80) pounds vand a maximum pressure of one` hundred iifty (150) pounds. Motor l is also adapted to automatically respond to an unintended reduction in pressureb'elow the chosenv minimum pressure of eighty (80) pounds tomove the throttledevice to an Emergency Preselected Throttle position `corresponding to a fast Ycruising output 'of the engine to insure safe operation of the airplane. Reference nu- 'merals V2 and 3 designate, respectively,.a selflapping lluid pressure pilots control valve `device and a fluid 'pressure self-lapping engineers control valve device, located at respective pilots and engineers stations on an Vairplar'ieto control the supply and release of fluid under pressure to land from the fluid pressure motor l for thereby controlling operation of theiengi'ne'. A pilots interlock valve device 4 is provided which is operative by pilot or co-pilot t0 one position for rendering iiuid pressure limiting means-associated with the engineers control device'B `effec-- tive to limit the range of operation of device3 to a Vernier range, allowing the engineer to tune the engine to synchronization with other engines while the piloty maintains control ofthe throttle through its full range, and operative to a second position for rendering said limiting means in eiective; thereby allowing the control valvedeasi vice 3 to be operative through its full range during warmup of the engine prior to taking off or for testing. Reference numeral' designates an engineers emergency selector valve device at the engineers station operative to a rst or normal vposition whereby either device 2 or devices may control operation of motor i `depending.upon the position of the interlock valve device 4. This device 5 is operative to a second or emergency position for remo-ving control of motor I from the influence of devices 2 or 4, and to` a third or emergency position for rapidly reducing. the pressure of fluid in device l to atmosphere to render device I effective to immediately assume' its Erm ergency Preselected Throttleposition, aspreviously mentioned.

` Referring to Fig. Vl-A, the fluidpressure motor 3 I is of the type disclosed and described in detail 'in Patent No. 2,413,287 issued to R. J. Bush, De cember 31, 1946, and assigned to the assignee of the present invention.

Briefly then, motor I comprises a hollow casing having a flexible diaphragm I which is clamped at its outer edge to said casing and is subject to the pressure of fluid in a control chamber Il at one side and to the pressureof huid in a spring chamber I2 at its opposite side. Chamber II is constantly open vto a cavity I3 in the casing by Way of a port I4, cavity I3 in turn being constantly open to a combined fluid pressure supply and control pipe l5 connected to the control valve device 3. Chamber I2 is constantly open to a passage and branch of fluid pressure exhaust pipe I6 which may be constantly connected to atmosphere or to an exhaust sump. A follower I1, disposed in chamber I2 and attachedito one face of diaphragm I0, accommodates one end of a compression control spring IB, disposed in said. chamber and interposed between said follower and a movable piston I3 slidably mounted in a casing bore coaxial with diaphragm I0.

Piston I9 is subject on one side to fluid at atmospheric pressure in chamber I2 and on the other side to the pressure Yof iiuid in chamber 2l which pressure in chamber 2l is the pressure of fluid in supply and control pipe I5, chamber 2L being constantly open to said pipe by way ofpassages 22, 23', a pipe 24, a passage 25 and cavity I3. `Since pipe I5 is normally supplied ywith iluid at a minimum pressure of about eighty `piston I6 and contains a differential area power piston means 3l which may comprise two axially arranged spaced apart and connected piston heads 32 and 33, piston head 33 being of greater diameter than piston head 32. Each head'32, 33

is slidably mounted in a respective bore 34, 35 i ,in cylinder 3U. Bore 34 is closed by an end wall which together with a limited portion of the adjacent face of piston means 3l defines a chamber 36 which is constantly open to atmosphere by way of port 31. A fluid pressure control chamber 38 is formed by the opposite face of piston means 3| and the wall 28. Between the two lpiston heads 32, 33 there is a dashpot chamber ,39 which is in constant communication with the control and supply pipe I5 by way of a choke 45, passages 4I, 42, the passages 22, 23, pipe 24,

passage 25 and cavity i3. Supply of fluid under pressure to the control chamber 36 and the release of iiuid under pressure therefrom is controlled by pilot valve means which will be hereinafter described.

The power piston means 3l is operatively connected to a rod or stem 43 projecting at one end' ythrough a central bore in aligned bosses 44 and. '45 disposed, respectively, inside and outside the casing. To the outerprojecting end of stem 43 is pivotally connected an operating lever 46 adapted to be connected at one end to a device to be actuated or controlled such as an aircraft engine throttle (not shown).

'Qf lever 45 is pivotally connected to one endy or aelioji The opposite end l 4 a link 4l', the other end of which link is pivotally connected to a` projecting ear of the casing. The lever is provided with an adjustable stop member in the form of a screw 48 which is adapted to engage with the boss 45 for defining a normal rest or idle position of lever 46. The lever lis also provided with means 49 for adjusting the fulcrum of the lever. l l Stem 43 also pro-jects on the opposite side 'of piston head 33 and extends through chamber 38 and wall 28 into a bore 56 in boss 5I attached to wall 26, which boss extends centrally through chamber 2l and into a central opening in piston I9. A sleeve 5 2 attached to piston I9 encircles boss 5I and a stop wall 53 is provided at one end of the sleeve for engagement with the inner end of stem 43. An axial bore, forming a iiuid pressure supply passage 54, is provided in stem '43 which bore is constantly open, by way of afport 53 and an annular passage 55, to passage-42 and thence to the supply and control pipe I6.

A -valve member 56 is disposed in chamberfIZ and is attached to the projecting end of stemr43. A portion of member 56 projects into bore 54-'in stem 43 While an oppositely extending portion projects into follower I1 attached to diaphragm Ill. A central bore 51 extends longitudinally through member 56'from end to end. A supply valve 53, having a iluted stem 59 slidably mounted in bore 51, is arranged to open and close bore 54 to bore 51 and thereby to ports 60 in member 56, thence to a port 6I in stem 43 and thereby to an annular clearance passage 62 encircling stem 43 within boss 5I which clearance pas* e is connected to control chamber 38. A rele e valve 63 is secured to one end of a pin 64, Vthe opposite end of the pin being connected to uted stem 59 of the valve 58. Pin 64 is of lesserdiameter than the diameter of bore 51 to allow- 'for passage of lfluid under pressure past it. A sleeve 65 extends into the bore 51 in member 56 and is slidably mounted in the member for engagement with release valve 63 which is operative 4for opening and closing ports 60, connected' as above mentioned to chamber 38, to a central bore S6 extending through sleeve 65. A head 61 is attached to the outer end of sleevej65 for contact with a boss 68 projecting from diaphragm IB, and a restricted port or choke 69 in said head connects bore 66 to' chamber I2, which chamber is open to the atmospherek or sump, by way of pipe I6. A bias compression spring 10 is disposed in bore 54 in stem 43, and is interposed between a seat 1I fixed in said bore and the supply valve 58 for urgingsaid valve to a normally closed position. A second bias compression spring 12 is interposed between a shoulder formed in the end of member56 and a flange 13 attached to head 61 for'urging sleeve 65 in the direction of diaphragm I0. Movement of sleeve E5 relative to member' 56 in the'direction of stem 43 is limited by contact between flange 13 and the end of Va flange 14 attached to member 56. Movement of member 56 away from diaphragm I0 is limited by engagement of liange 14 With a rib 15 attached to follower I1. A

Referring to Figs. 1 and 1-A, both the pilots control valve device 2 and the engineers control valve device 3 are substantially alike with the exception of uid pressure means comprised in the last named device for limiting operation thereof to a Vernier range. For the sake of brevity, lWhere the following description of device 2 also applies to devig the description Will'gg.

andere `be'-dupHeated and identical-'elements will-be designated by the samefre'ference numerals.

@Both ofthe valve devices 2 and 3 are of the type described `in detail in Patent No. 253983877 issued'to'A. J. Bent, April 23, 1946, and assigned tothe'assignee of ther present` invention. Briefly, therefore-each of the control valve devices-2 and 3 comprises a self-lapping valvel portion enclosed in a casing and also comprises an operators lever portion which is mounted on the casingand is arranged to actuate said valve portion.

The operators lever portion comprises a pedestal"|'0| suitablymounted -oncasing |09 and having two spaced apart upstanding lugs |02 forr supportingthe hub |03 `of an operators lever' |04. The hub |f03is pivotally connected to said lugs by-a shaft |-05. A cam |06 for operating the selflapping valve portion, later to be described,y is ariang'edto. be positioned bylever |04. The cam is'connected by means cf'a pin |01 tohub -|03 andlis-urged against an adjusting -screw `|08 by a spring |09 to-dene a chosen operating position,--the adjusting screw being -mounted in the hub.

The self-lapping lvalve portion comprises a flexible diaphragm ||-0 having at one side a luid pressure chamber `constantly open vtoauid pressure delivery passage ||2 by way of a restricted stabilizing passage I3, and Vhavingat the opposite side a-uidvpressure chamber |14 constantly'opento a fluid pressure passage ||5. A control spring ||6 is disposed in chamber ||4 urging-diaphragm H6 in the direction of chamber A iiuid pressure supply chamber ||1 ris provided in the casing which is connected to a Ai'iuid pressure vdelivery passage |8, and fluid pressure'delivery Ychamber |20 is a-lso provided which isconnected to 'delivery passage-H2. A slidable valve seat sleeve member |2| extends through bore ||9, chamber |1, and a bore |22 into a spring chamber |23 formed in pedestal l0|. Attached to member |2| is a stem |24 which projects through an opening in pedestal |0| for engagement with a cam follower |25 pivotally secured to the lugs |02. A spring |25 disposed in chamber |23 urges stem |24 against follower |25 andsaid follower against cam 06'.

yAsupply valve chamber |21 is formed in valve seat sleeve member |.2| which is open, by way of ports |28, to supply chamber |I1. Contained in this chamber ||1 is a supply valve |29 which is for the purpose of opening and closingf'communication between chamber |21 and a bore |30 in the'member |2| which bore is adapted to connect said chamber I1 with delivery chamber 20. The valve |29 is provided with a fluted stem |3| which is slidably guided in bore |30. A pilot valve |32 is provided which is arranged to seat on valve |29 for opening and closing communication between chamber |21 and a relatively small port |32 in valve |29 extending between bore |30 and a bore |33 in the sleeve member. The valve |32 is provided with a stem |34 which is slidably guided in the bore |33 in the valve stem |'3|. A bias spring |35 disposed in chamber |21 is provided which urges valves |32 and |29 to normally closed positions.

Delivery chamber 20 is open to a hollow sleeve .|39 extending through a bore |40 which extends between chambers |20 and and through diaphragm H9 into chamber ||4. Sleeve |39 is secured to move with diaphragm ||0, being attached to a follower |4| at one side of said diaphragm which is clamped to a follower |42 at the opposite slide of said diaphragm and forms ra seatifor'spring 1129. A..hollowfsleevefl|43.: secured inacasingbore |144 byfscrewlthreads, also .projectsv into l chamber v2| 4 :coaxially 'withfA and spaced away fromlsleeve '|3'9,.^the interior-ofthe vslf'z'eve |43' beingfopen to a fgroove yar'1'd.passage"|46 .by way -of Aports |45. .A .floating hollow sleeve |41, slidablyf mounted.r at; its .opposite ends in sleeves |39 and.|43,.rcompletes aconduit connectingdelivery chamber |20 to exhaust .passageI |46 via the hollowsleeve members. lSealing rings.=are provided fat-various points to jprevent leakage past slidable `ioints.

A release valve Vis disposed in sleeve |39 for .openingcan'dfclosing theichamber |20 to exhaustfpassage; |46 'via the `connected sleeves |39, |4.1,.1an'd1. |43'. utedrsteml 5 slidably .mounted in :albore |52 'inf-sleeve |39, guides .said valves-.in its travel. fAreleaseizpilot valve |53.is connected to a stem.f|5'4.slidably mounted in a central 'bore extending 1thrroughthe valve |50 `and stem"|`5|. Ports in valve -|i501connec't thel bore therein lwith bore |52 insleeveflllll, and pilot valvei |-53efcon trols communication Yof uid under -,pressure throughfsaid ports. A bias `compression 'spring |51fis disposed in.y sleeve |'39interposed between va vforaminated ,partition and the projecting end of =stem Y |54 in `such a manner as to .furgepilot valve 15S-'against the .projectingv end `of stem y|34 attached tof-'the supply pilot valve |32. Therelease valve |59 .is loosely connected Yto the projecting yend of thesupplyvalve-stem; |3| an'dis held in a normally seated position `by action o spring 3-5.. f

The controlspring |6 seats; atfone end on-a washer member 460 carried :by sleeve |43, so that by Yinserting Ya "Wrench into a socket vprovided inthe outer'end of said sleeve theinitial compression. of saidl spring may be changed by screwing sleeve |43 in or out of bore |44. Alock nut |6| isprovided for preventing unintended movement of sleeve |43 lout of a desired adjusted position.

Aszwill apply only to ythe engineers control valve device 3, `and Yas shown in Figs. l-A and .4.. 2, the fluid pressure limiting means comprises a lockout lever `which is attached'to a ring |66 slidably mounted on a portion |61 of hub |03. The -lever |65 is `operatively connected to an actuating piston 169 slidably disposed in la bore |10 in casing v|00 and connected to said lever by a rod |1| and a link |12. A springl|13 in bore |10 at one side of piston |69 .is .arranged to urge said piston in the direction of a fluid pressure chamber |14 at its opposite side, said chamber being open to a fluidpressure passage-|15 leading to theengineers emergency selector valverdevice -5. A -shoulder |16 is formed in hub |03 for engagement with a corresponding shoulder 11 on lever |65 to limit travel of operating lever |04 whenr positioned as shown in the drawing. A shoulder |18 in hub |03 is provided to engage a shoulder |19 on lever |65 .to denne an idle position of lever |04 as indicated by a dot and dash line |68 n Fig. 2.

Referring to Figs. 1 and l-A, the uid pressure supply passage ||8 in the pilots control valve device 2 is connected by way of a branch passage and connected chambers and |8| in a .pipe bracket |82 to a pipe |83 leading to the engineers emergency selector valve device 5 by way of a passage |84 in a pipe bracket |85 secured to the engineers control valve device, therey being a check valve |86 'in bracket |82 between said chambers therein to allow fluid under pressure 'to flow only inthe direction Voi said supply passage |18 in said pilots control valve device 2. Delivery passage ||2 in pilots control valve device 2 is connected to the selector valve device 5 by way of a branch passage in bracket |82, a pipe |81 and a passage |88 in bracket |85. Passages ||5 and |46 in pilots control valve device 2 are both connected to the fluid pressure exhaust pipe |6 by way of a common cavity |89 in pipe bracket |62.

In the engineers control valve device 3, the i'luid pressure supply passage |15 is connected to the selector valve device 5 by way of a branch passage in the bracket |85. Fluid pressure supply passage is connected to a uid pressure supply pipe |90 by way of a branch of said passage in bracket |85, pipe |90 in turn being connected to a fluid pressure'reservoir |9| adapted to be supplied with fluid under pressure from a suitable source such as a compressor (not shown). Fluid pressure delivery passage |2 in engineers control device 3 is constantly open to the combined uid pressure supply and delivery pipe |5, connected to motor by way of a branch of passage ||2 in bracket |85. Passage in valve device 3 is connected by way of a branch of passage ||5 in bracket |85 to selector valve device 5, and passage |46 in device 3 is connected to a branch of exhaust pipe I6 by Way of passage |46 in said bracket.

Referring to Fig. 1 the pilots interlock valvedevice 4 is provided with the usual casing |95 having a fluid pressure supply chamber |96 constantly open to the fluid pressure supply pipe |90. This chamber is adapted to be connected to a Iiuid pressure delivery chamber |91, formed in a bore |98 between two spaced apart sleeve bushings |99 and 200 mounted in said bore. Chamber |91 is also adapted to be connected to a fluid pressure delivery pipe 20| having a connection tothe emergency selector valve device 5 by Way of a branch of said pipe and a passage 202 in pipe bracket |85. Within the casing there 8' actuates rod 208 upwardly a greater distance thanthe supply valve 206 travels to seat.

The engineers emergency selector valve device 5 may comprise a casing having a valve seat section 220 and a cap or cover section 22| which are secured together and to the pipe bracket |85 adjacent to the engineers control valve device 3. The cover section 22| is provided with a bore containing a rotary valve 222, the face of which slidably contacts with the valve seat face formed in the` valve seat section 220 and the peripheral edge surface of which slidably contacts with the cover section 22| within said bore. The rotary valve is operatively connected to the one end yof an operating stem 223 suitably journaled in a sleeve 224 attached to the cover section 22| of the casing. The opposite end of stem 223 terminates within sleeve 224 and has secured thereto by means of a pin 225 an operating knob or handle 226 through the medium of which the stem and thereby the rotary valve 222 may be rotated. A sleeve 2.21, attached to handle 226, encircles the end of stem223 and is adapted to reciprocate and rotate within an accommodating annular groove 229 in sleeve 224. A guide slot 229, the development of which is shown in Fig. 3, is formed in sleeve 224, which slot provides three Yspaced. apart shoulders 230, 23|, 232, against is a fluid pressure exhaust chamber 203 formed by a groove in bore |98 encircling bushing |99, chamber 203 being open to a branch of fluid pressure exhaust pipe I6. A reducing valve device is provided in pipe |90 to provide suitable working pressure. A central bore 204 in bushing 200, extending between chambers |96 and |91, accommodates a luted valve stem 205 slidably mounted' therein. Disposed in chamber |96 and attached to one end of stem 205 is a supply valve 200 arranged to engage or disengage with a seat formed in the end of said bushing for opening and closing chamber |96 to bore 204 and consequently to chamber |91. A spring 201, disposed in chamber |96, is arranged to urge valve 206 toward its seat in bushing 296. A release valve 291", disposed in chamber |91, is'attached to the opposite end of stem 205, and is adapted to engage a seat formed in the projecting end of a rod 208 which is arranged to be reciprocated in a central bore 209 extending through bushing,r |99 for opening and closing chamber |91 to a central passage 2|0 in said rod. Passage 2|9 is arranged to be open to exhaust chamber 203 by way of aligned radial ports 2H in bushing |69 and rod 208. The opposite end of rod 268 is operatively connested by anni; 212 to a pilots lever 213, pin connected at 2|4 to casing |95. Link 2|2 is eccentrically connected to lever 2|3 so that movement of said lever from its Pilots Control position as shown to an opposite Engineers Control" position indicated by dot-and-dash-iines which projecting ends of pin 225 may seat to dene three positions, Pilots Control, Emergency Engineer-s Control, and Emergency Preselected Throttle, respectively, of the selector valve device. Pin 225 nts in bores in sleeve 221 and a slot 293 in stem 223 so that said pin and stem Ywill rotate with handle 220. Clearance is provided between the end of sleeve 221 and the end of groove 228 so that from the Emergency Engineers Control position handle 226 may be depressed and rotated to Emergency Preselected Throttle position, moving pin 225 consecutively downwardly and toward shoulder y232 within guide slot 229, and downwardly in slot 233 as subsequent rotation of said pin rotates stem 223. A compression spring 235 is arranged to bias handle 226 upwardly. A compression spring 236 is provided for loading valve 222, interposed between said valve and a seat member 231 arranged to rotate with stem 225 and slide in an accommodating groove in cover portion 22|.

Operation In operation, let it be assumed initially that the operating lever |69 of the pilots control valve device 2 is in idling position with both its supply valve |29 and its release valve |59 closed, that control spring I9 or device 2 is adjusted for substantially rio-initial compression, that operating lever E64 cf the engineers control valve device' 3 isin idling position also with its release valve closed and its supply valve open; that control spring ||5` cf device 3 has been adjusted for an initial compression sulicient to balance with a delivery pressure of eighty (SU) pounds in chamber for example; that operating lever 2|3 of pilcts interlock valve device 4 is in Pilots Control position; that the engineers emergency selector valve device E is in Pilots Control position; andfurther assume that reservoir i9! is charged with fluid at a pressure er" nve hundred (500) pounds ior example.

Fluid under pressure from reservoir |9| then flows by way of pipe |99 and a branch thereof 7to passage H8 in pipe bracket |85 whence it flows tothe supply chamber l |1 of the engineers control valve device 3 and to the correspon 'g t to travelffbetwecnz Idling and Vernier Limit 9: chamber' |.I I irr. thel pilotsv control valve deviceY 2 bywayof thearotary valve seat 22,6,1the rotary valve chamber, a cavity 24S-inthe valve-222, the passage |84,l the pipe: IMI-chambers ISI and Idil .infbracket-If82, andpassager |I8lin device 2. With supply valve |29- closed inA device 2, iifuid under pressure inchamber I |.-'I: at this time is thereby prevented: from, flowing todelivery chamber |25 of-saidfdevice At the same time fluid: under pressure vsupplied;v to passager IIS in bracket |85 flow-shy Way oli-connected branches of said passageto supply chamber I I1 of theengineers con trol valve device Siandrthe supply valve |2` thereof being open flows `through ports |28; vchamber |221 and' bore I3IJ in sleever I2 tinto delivery cham- A,berV I2D of said device, whence it flowsbyway ci delivery passage I|2 in device 3, the branch thereof in bracket |85', and the combined fluid pressure supply-and control pipe I5 to the-cavity |3.-in-.uid pressure-motor |1-. Inv motor I uid underpressureimcavfity I3 ows to control. chamber -ItIffbyfWay-of port I4; and also to chamber 2| by jwayof" passage-22.5, pipe 24,. andpassages 23 and 22".. From; passage 22V uid under pressure also icyv's-lto dashepot chamberg byf way of passages 42, 4I and chokef4ll; and by way of passages andeannularpassage 55.v to supply passage 54 in stemgfwhere the seated supply valve 58'- prevents the--owof fluidunderpressure from. saidpassage 541 When lpressure of-uid inchambers II, 2|, andlv38 inlmotor If reaches a: value ofeighty (Se) ypounds-'the piston f arrangement 3| assumes its `positionasshown in thedrawing maintaining.. the operatinglever-46fdisposed; in yits idle positicn,.the piston, 1.911 assumes its. normal. positicn` seated `againstf shoulder. 2 E Lagainst l opposition of spring JB; asfshownVand'diaphragm- It* assumes a posi? tientas. shown.r inwhich supply valve` 5S andres- .haustrvalve 63. are seatedfand closed'. At the same time;` int device. Y3, the pressure of fluid in ,chamber` I.,4 open` to. delivery,v chamber lill', by wayV of..7 choke |-I.31 becomes: elective to. overcome actiouofispring Llland move diaphragm-I lil in the direction-of chamber I Iilsuilioiently to close .thef-supplylvalve |29 and thereby. maintain the minimum pressureoffeghty. (Bill-pounds, for ex- |=90`rflowstbywayfofthefreduoing valve devcefto supply y.c'liamber' |19 65 intheV pilots interlock" Valve 'deviceflkat afreduced. pressure, whenceitflows Vby lwayof.unseatedfsupplyvalve 206;'bore 2Il4cham.- ber"I!tIfin'1device=4itorpipe lwconnected to pas sage`v 2ll'2fin1 bracket I 85: From. passagev B?? the duid 'at' reduced; pressure flows by' wayy ofV a branch? ofsaidl passage in sea'tYZ-Zfl,Vv and a cavity 241km .zrotary valve 222-' to apassage-'I l5 in seat 225; bracketfl'; and-"engineerslcontrol device A3,

Ovl'flierev it flowsto' chamber I'Iibenea-th` piston vI 69 "andi becomes effective to`4 position said piston against action or spring lijinwhich position it shown in` the 'drawing'.v The lockoutlever |65 connected-Cto. piston lglthrough link H2 and rod ,"III attached tosaidpiston, istherefore positioned Vas.,sl'1o.wn. for limiting. movement of.. operating lever-...|04l of the engineers controLvalvedevice 3 stabilizing` passage. |f|3 to chamber 10 positions as indicated by the respective-dot-anddashlines in Figs. l--A and 2.-

NOW let it be assumed that the pilot desires to increase the speed of the engine to a degree above idling speed. To accomplish this he moves the lever |04 of control devicel 2 out oi .Idling position in the direction of *"Full` Throttle position and Ythis movement rocks cam- I'dandV displaces stem |24 downwardly, as viewed in the drawing, moving the supply valve seat formed in member |2I Iaway from the supply valve |723 which is prevented from moving. therewith by the. release valve seated on follower IIIJ and connected. to valve |29.- Fluid underv pressure then. flows past the unseated. supply valve |29 to chamber I 2D and thence through. passage II2 and pipe |31 to passage |88 irl-pipe bracket |85 secured to the engineersV control Valve` device. 3', and from'said passage |88 to chamber ||4in device 3 by way of alcavity 248 in rotary valve 222 and passage ||5.

In. device 3,. uid under pressure thus supplied to chamber ||4 deects diaphragm III) in the direction of chamber III, .carrying follower |4I,

release valve |50., and release pilot valve |53 with it,.and consecutively unseating supply pilot'valve |32 and supply valve |29, whereupon fluid under pressure Hows from chamber |21 to delivery chamber` |2Il,. thence through passage ||2 and pipe I 5 to chambers I I,- 2| 39 and supply passage 54 in uid' pressure motor I constantly open to pipe I5 as previously described.

In the' pilots control valve device 2, fluid under pressure supplied to chamber |20. flows throughL restricted stabilizing passage |I3 to chamber III abovediaphragm I|0 and'when the pressure of fluid in chamber III increasestoA a sufficient degree with respect to the opposing force of spring IIS, said pressure moves diaphragm- IIU in they direction ofi chamber` |`I4 which is. open to theatmosphere -via passage |=I5 andpipe I6, therebypermitting'closing of.` the supply. valve |291 by actionvof. spr-ing. |35 to thus limit.r the pressure of. fl-uidobtainedr in chamber 2|). in accordance with the position of the operatinglever |04. Sincechamber |2`Ilof the pilots control.4 valve device 2` is in communication with chamber |I4 of theengineers control valvedevice-'3A the pressureof fluid in saidchamber I I4ris also in accordance. with the positionof the operating. lever I U4 of device 2.

At substantially the same` time, inthe enjgineers control valve device-3,fluid-under pressure supplied to chamber |20- flowsy by way of III above diaphragmV I-I-II; and whenrthe pressure of fluid in chamber HI increasesintdegree suiiicient to overcomethe opposingiaction of pressure of fluid in chamberA |I4 aided by spring I It-7 the diaphragmfllfwill be moved 'in the direction of chamber II4 topermit closing of-the supply valve |219-by spring |35 to thereby limit-the pressure of fluid supplied to= the fluid pressure motor I via passage ||2 and pipe Iiiinl accordance with the pressure of iluid provided in chamber I I4 of'device: 3 by the-spilots control valve device 2.

In the uid pressure motor I the pressure of duid attained in control chamber I-I deflects diaphragm I 0in thedirectionof chamber I2 in opposition to the force of@ spring Ito a position in which such forcebalances the actionof the pressure 'of said fluid, and this deflection moves sleeve E5 within member` 55 to unseat supply valve58-v againstthe'opposingfaction of spring .TIIf allowing fluid under: pressure to now from supply passage 54 to chamber 38 by way of bore 51, groove 60, and passages 6I and 62. Since a greater area of the piston assemblage is exposed to the pressure of fluid in chamber 38 than to the same pressure of fluid in chamber 36, uid under pressure in chamber 33' causes the piston assembly 3| and stem 43 to move in the direction of chamber 39. The stem 43, as it moves relative to sleeve 65, brings the member 56 attached to said stem into contact with supply valve 53, thus closing off further supply of fluid under pressure to chamber 38 at which time further movement of piston assemblage 3| ceases. The stem 43, as it is thus moved, actuates the operating lever 46, assumed to be attached to the engine throttle, to a position for causing acceleration of the engine to a degree determined by the increase in pressure of fluid supplied to chamber I I. Action of pressure of fludin dash-pot chamber 39 is such as to dampen motion of piston assemblage 3| to more accurately position lever 46 and prevent over-travel and hunting of motor I. Pressure of iiuid in chamber 2| maintains piston I9 seated against shoulder 26.

Since the position of operating lever 46 of motor I connected to the engine throttle determines speed of the engine, which -position is, in turn, determined by the pressure of fluid supplied to control chamber II by the engineers control valve device 3, which is proportional to the pressure of fluid supplied to chamber I4 in device 3 by the pilots control valve device 2, and further, since the last named pressure of fluid is determined by the relative position of the operating lever |04 of the pilot's control valve device 2 between Idling and Full Throttle positions, it will be seen that the speed of the engine will correspond to the position of said lever |04 out of idling position.

If the pilot desires to further increase the speedof the engine, he moves the vcontrol lever |04 of control valve device 2 further in the direction of y Full Throttle position to thereby increase the pressure of fluid in chamber I I4 of the engineers control valve device 3 which responds to such an increase to correspondingly increase the pressure of fluid in control chamber |I of fluid pressure motor I, and render said motor responsive to supply fluid under pressure to power piston assemblage 3| and thus move operating lever 46 to aV position for effecting an increase in the speed of the engine in proportion to the degree of movement of said lever |04.

If the pilot desires to reduce the speed of the engine, he moves lever |04 of the pilots contr'olf valve device 2 back toward Idling position.

This movement allows spring |26 to move member I2I upwardly, as viewed in the drawing. carrying pilot valve |32, supply valve |29, pilot valve |53 and release valve I 50 with it to con-r secutively unseat release valves |53 and |50, allowing fluid under pressure to ow from chamber II4 in control valve device 3 via chamber |20'Vin lcontrol valve device 2 to exhaust pipe I6. The flow of fluid from said chamber |25 being by way of bore |52 in sleeve |39, floating sleeve |41,

Isleeve |43, ports I 45, passage |46 and chamber vpilot valve |53 and release valve |50 to thereby Jlimit the reduction in pressure of fluid in cham- I2 ber I I4 of control valve device 3 in accordance with the new position* of control lever |04 of fthe pilots control valve device 2.

This reduction in pressure of fluid in chamber IlI4 of the control valve device 3 allows pressure of fluid in chamber III above diaphragm IIO to become effective to move said diaphragm downwardly in the direction of said chamber II4, carrying follower`|4| with it and thereby consecutively unseating release pilot valve |53 and release valve |50 to allow fluid under pressure to flow from chambers II, 2|, 39 and passage 54 in fluid pressure motor I via chamber |20 in de'- vice 3 to the exhaust pipe I6 by way of bore |52 in sleeve |39, floating sleeve |41, sleeve |43, ports |45 and passage |46 in casing |00 and bracket |85. The reduction in pressure of fluid in chamber I 20 is reflected in chamber III above diaphragm IIO'by way of stabilizing passage ||3 and when said reduction is of sufficient degree. the combined action of the pressure of fluid in chamber |I4 and of spring I|6 moves follower I4I and diaphragm IIO to reseat valves |53 and |59 to thereby limit the pressure fluid in fluid pressure motor I in accordance with the pressure of fluid in chamber I I4 of device 3.

In fluid pressure motor I, the reduced pressure of fluid in chamber II allows control springIB, acting through follower I1, to deflect diaphragm I9 in the direction of said chamber a distanceA proportional to the degree of the pressure reduc` tion to thus render spring 12, which urges head 61 of sleeve 65 against vboss 68 of diaphragm I0, effective to move said sleeve away'from release valve B3 to allow pressure of fluidin chamber 38 to reduce past the unseated release valve 63 to bore 66 in said sleeve and thence through the restricted release port 69 to chamber I2 and exhaust pipe I6. As soon as pressure of fluid is reduced in chamber 38 sufficiently with respect to pressure of uid in chamber 39, the piston assemblage 3| will move in the direction of chamber 38, carrying stem v43 and attached member 56v with it until release valve 63 reseats on sleeve 65 to prevent further release of pressure from chamber 38, whereupon further movement of piston means 3| ceases. The stem 43 asit is thus moved actuates the operating lever 46 toward Idling position and thereby assumes a position between Idling and Full Throttle positions in accordance with the degree of pressureA reduction in control chamber II, thus reducing the speed of the engine. Again action of dashpot chamber 39 in combination with action of choke 40 causes a snubbing action on the piston assemblage 3| during movement which assures the stabilization and accurate adjustment of sa-id assemblage. The pressure of Huid in chamber 2| maintains piston I9 seated against shoulder 26 during normal operation of motor I between-the assumed operating pressure limits of eighty-() to one hundred fty pounds. I y If the lever |04 of the pilots control valve device 2 is returned further toward Idling position, a further reduction in pressure of fluid in chamber II4 of the engineers control valve device 3, and in chamber II of the fluid pressure motor I is effected. Il lever 104 of device v2 is returned to Idling position, pressure of fluid in chamber I I4 of device 3 is reduced to atmospheric pressure and the device 3 is caused to function to reduce the pressure of fluid in control chamber elmeg-'zio otfmotor I; the'diaphragm Il! deeotsl accordingly; allowing theunseatingof release valve E3to reducefthe pressure of fluid in chamber 3B. In response to the reduction inthe-pressure of uid inzchamber 38 the pistonassemblage 3| in motor I will function to reposition operating lever 4G and reduce the speed'of the engine in proportion to th'edegree offreduction in pressurein chamber whereupon release valve 63- reseats to prevent further reduction of pressure in chamber 38. When pressure of fluid in chamber Iliin motor I is'- reduced to eighty (80) pounds, the operating lever lili moves to` Idling position' asshown in the drawing.

It will thus be seen that when the operating lever |04 of the pilot-s control' valve device 2 is returned' to Idling position, the fluid pressure motor-I is caused to respond to return its lever 46 to its corresponding Idling position for actuating the throttle to idle the engine speed, while upon movement of said lever |04 up to and vincluding Full Throttle position, the lever 4S of motorl will be correspondingly positioned simultaneously to obtain'y corresponding speed offthey engine.

When the pilotis controlling the speed of the engine; the engineer may desire to make slight adjustment ofthe-speed or the engine in order to bring its speed into synchronisni with the speed of other engines on they sainey airplane. Let it be assumed th'at'the engineer vdesires to slightly increase the Speed'of the engine, He will move lever |94 ofthe engineers control valve device 3 out of"dling position in the direction of the Vernier Limit position. This movement will rock' cam meer device Band cause downward movement of stem |24" and therebyssleeve I2! in opposition4 tov spring 12S 'causing said sleeve |2| to unseaty from supply valve |29' which s restrained from' movingwith said" sieeve bythe spring |16- aoting through iollower |4| and release `valve |59. Fluidunder pressure then flows fromY chamber I2l--to `delivery chamber |2l and thenceV to control chamber" Il or fluid pressure motor Pressureof fluidin diaphragm chamber III of: the device 3'is the same-as that existingin chamber lili, chamber l I l being'open to chamber |2il byway of stabilizing passage H3, andwhen this-pressure is increased sufliciently to overcome the opposing combined. action of f pressure of fluid in chamber H4. and springV |16 diaphragm Il!) is deflected downwardly allowing spring |35 toreseatsupply valve 29 to provide a pressure of fluid in chamber of fluid pressure motor1 I which will be increased above that called for by the position of theflever lill! of the pilots control valve device 2 by an amount corresponding to the position of lever H14 of the engineers control valve device 3, The fluidpressure motor I will respond to the increased pressure'of iluid in chamber II as will be readily understood from previous description, to move its ylever |46 in the direction of Full Throttle position to a position corresponding to said increased pressure and thereby eiect the increase in speed'of the engine -desired by the engineer.

vOnly la relatively small change in` speed'of' the engine is necessary to bring it into synchronism with any'other engine on the airplane when the engine is under control of the piloti so'ithat, while l the, leverr 2|3- in pilots interlock` valve device- 4 is1positionedassliownin the drawing, the maximumtravelof the lever itlof the engineers control valve= device 3A out of` Idling position is; limitedptomovementzto theposton Vernier Iii-miti in whichv shoulder |15. on hub' I [i3` attached to said lever ||l4 isin'contact with shoulder` Ill of lockout lever I5Lwhich thereby'prevents further movement'of lever |84 in the directionof "Full Throttle" position. The purpose of `the limitation is. to prevent-the engineer from intertering with thefpilots control' ofV theengine dur,- ing flight beyond the minor adjustments necessary to bring the: engineinto synchronism with other engines.

While the engineers emergency selector valve device 5" is in its normal Pilots Control position in 'which itis shown in the drawing, if the pilot desires to render the engineers control vvalve device 3"ef1ective to control the speed oi' the engine through itsfull range, he may remove the limitation imposed upon movement of lever |ll4 in saididevice B'by moving lever 2|3 of interlock valve device4 from Pilots Control position to the opposite Engineers C'ontrolposi. tion. Such a changeover of valve 4 would usually be desirable'during warm-up period of the engine priory to take-oir to allow the engineer to study the performance of the engine while the operating: lever Ill!!v of pilotsv controll valve device 2 wouldA remain ,in Idle position.,

Thelever 213 asit moves to Engineers Control position movesrod. to a position out of contact with release valve 2M' and allowing spring 29T to close ythe. supply valve-20B. Fluid under pressurein chamber: |14 under piston IBB in the engineers control valve device 3 then flows by way of passage I'IE, cavity 2Min rotary-valve 222, passage 2l2, pipe2lll,v chamber |91 in valve device 4 and the unseated release valve 2'I in saiddevice to exhaust pipe I6; Pressure-ofliuid thus reduced in chamber |14' allows spring |13 to move piston |59 in the direction of chamber |14 moving lockout leverv |i5, connected thereto, with it untill as Will'be seen' by referring to Fig. 2. shoulder |19 on lockout lever 165 contacts with shoulder |18 on hub ID3 of lever Hill, or until piston IEQ'contacts theend Wall of bore I'l exposed to chamber |14', lockout lever |65v is thus so positioned that'movement of lever ltll of the engineers control'fvalve device Bis no longer limited to the range of movement between Idle and Vernier Limit positions, but is now. operable between the extreme limits of- Idle and Full Throttle positions.

The engineer may now move 'lever H34 of control valve device?" to any positionfup to and including Full Throttle postionffor warming up and testingthe engine.v Movement of lever I of device 3- to a new position in direction of Full Throttle position,y as was described'n .detail in regard to operation of 'device 3 within the range between Idle and-Vernier Limit positions, renders said device 3 responsive to supply fluidto control chamber I I in fluid pressure motor I at an increasedpressure in accordance with position of` said lever IM and to maintain said pressureso long'as said lever remains so positioned, while the` increased pressure of iiuid in said chamber II s renders; motor I responsive to move lever 4E toa new yposition* for increasing the speedpof the engine in accordance said increased pressure in chamber I IL it will be appreciatedthat with the pilots interlock valve device 4 in Engineers Control position andthe lever |94 of the pilots control valve device. 2in Idle position and the engineers emergency selector valve device 5, posi,- tioned asshown-,inf the drawing, the operating lever |84 of. the-engineers control valvefdevice may be moved from any" position intermediate Idle and Full Throttle toward and including Idle position and thereby render said device 3 responsive to reduce the pressure oi fluid in control chamber I I of fluid pressure motor I and thus effect positioning of lever 43 thereof to reduce the speed of the engine in accordance with the new position of the lever |04 in device 3.

Under the above conditions, the pilot may take control of the engine away from the engineer by .returning lever 2I3 of the pilots interlock valve l|'I3 to return the lockout lever |55 to its position in which it is shown in the drawing. The lever |04 of device 3 is therefore again limited to movement between Idle and Vernier-Limit positions which latter position is dened by contact of the shoulder |11 in lockout lever |05 with vshoulder |16 in hub 303.

If, at the time the pilot returns lever 2|3 to its Pilots Control position, the position of lever |04 ci the engineers control valve device 3 is between Vernier Limit and Full Throttle position, the consequent return of lockout lever |65 to its position as shown in the drawing will return said lever |04 to Vernier Limit position by engagement between shoulders I'IB and I'I'I as will be seen by referring to Fig. 2.

While an engine is under control of the pilot, that is, when the pilots interlock valve device 4 is in Pilots Control position and the engineers emergency selector valve device is in Pilots Control position, as shown in the drawing, if it should be desirable for the engineer to take oontrol of the engine from the pilot, for repair of the engine or for reason arisingl from an emergency situation, the engineer may accomplish this by turning the operating handle 220 of device 5 to Emergency Engineers Control position; blanking off, in bracket |85, passages |80 y and 202, and connecting passages H5, |34, and

| to passage |46 and thereby to exhaust pipe I6. Pipe |83 connected to supply chamber l II in the pilots control valve device 2 is vented to atmosphere via the now connected passages |84,

|86 and pipe I6, and the pipe |81 connected to the delivery chamber |20 of said device 2 and to passage |88 in bracket |85 is now blanked ofi -so that the pilots control valve device 2 is rendered ineffective. Chamber |'I4 beneath piston |69 in the engineers control valve device 3 is vented to atmosphere via the now connected passages |15, |46 and pipe I6 so that spring |13 moves piston |69 to its limit of travel in the direc-v tion of said chamber |74 thereby moving lockout lever |05 to its no limiting position to allow full range movement of lever |04 of device 3 between idling and Full rFhrottlc. positions. Pipe 20| connected to delivery chamber |91 in the pilots interlock valve device 4 and to passage v2512 in bracket |85 is now blanked off thereby rendering said device 4 ineffective. Chamber |I4 in the engineers control device 3 is vented to atmosphere via the now connected passages |I5, |46 and pipe IS, and with operating lever |04 of said device 3 at Idling position, said device 3 re- 16 mains in its initially 'charged position in which the assumed minimum pressure of eighty (80) pounds is'maintained in its delivery chamber |20 and hence in control chamber II of fluidpressure motor connected to chamber |20 via pipe I5.

The engineers control valve device 3 is now rendered effective to control the speed and operation ofthe engine through iiuid pressure motor I without interference from the pilots control valve device 2. The engineer may, if he so de,- sires, either increase or decrease the speed of the engine by movement of operating lever |04 of device 3 through its full range, thus influencing the operation of the fluid pressure motor I, which will be understood from previous description.

If the engine is then repaired or' normal conditions otherwise established, the engineer may In the event of slow reduction in pressure of uid in the supply pipe |90, due, for example, to accidental leakage of fluid under pressure out of the system, if said pressure reduces below the pressure of one hundred iifty (150) pounds which is the previously assumed desired maximum working pressure for the' fluid pressure motor I, it will be appreciated that the maximum pressure that can be delivered by either-of the control valve devices 2 or 3 to fluid pressure motor, I under this condition will be the reducing pressure of fluid supplied to said devices from pipe |90. As a consequence'of accidentahreduction in the pressure of fluid in pipe |80 below one hundred fifty (150) pounds7 pressure of fluid may slowly reduce in chambers I I, 2| and 39 in motor I, when such pressure in pipe |30 becomes less than that previously held in said chambers and said motor will respond to such reduction and move the lever 43, if positioned for operation of the engine other than idling, in the direction of Idling position distances corresponding to such reduction, with the result that the engine will thereby be slowed down. If the accidental loss of supply pressure causes the pressure of iiuid in chamber 2| to reduce below the assumed normal minimum pressure of eighty (30) pounds,

the spring I6 will become effective to move piston IQ in the direction of said chamber 2| until rib 53 attached to said piston contacts a shoulder in the end of stem 43, after which further movement of piston I3 by spring I8 in the direction of chamber 2| carries `stem 43 with it and thereby moves lever 46 toward its Emergency speed, with the result, that during the time of `reduced engine speed, safety of airplane might be endangered.

If the `engine begins to fail slowly due to the above vslow reduction in pressure of supply iluid, the engineer may, Aif he so desires, move the 'emergency selector valve device 5 to the Emergency Engineers Presclected Throttle position by turning the operating handle 226 of device E, as shown in Figs. l-A and 3, iirst to Emergency lilngineersA Control position, and then depressing and rotating it until pin 225 engages shoulder 232 in groove 229. Referring to Fig. 5, in Emergency Preselected Throttle position of the selector valve device 5, the supply passage vI'Iil connected to supply pipe I9!! in bracket |85 and to supply chamber ||'I in the engineers control Valve device 3, and the passage |81! connected to the supply chamber IH in the pilots control valve device 2 via pipe |83 are connected by way of a cavity in rotary valve 222 to passage |46 thence to exhaust pipe IE, while passages `rH5, |88, |15, and 202 in bracket |85 are blanked off by said valve 222. At this time, therefore,

,jt-he `pilots control valve device 2 is ineffective -to influence pressure of fluid in -iluid pressure lmotor i., 'ha-ving its supply chamber IH open to exf 'haust pipe I6 connected to' an yexhaust sump or `to atmosphere, and having its delivery chamber |21! connected to pipe |81 and passage |88 in bracket |85 blanked off by valve 222 in device E.

With the supply chamber of control device 3 vented to atmosphere by selector Avalve device 5 in "Emergency Preselected Throttle position, operating `lever |04 and thereby cam IGS of control valve device `3 will be so positioned that sleeve member |21 is disposed away from supply valve IJI'I, thereby allowing pressure of fluid in chamber 2| of fluid lpressure motorv vI to rapidly reduce `via pipe I5, passage II2, delivery chamber |29, the `unseated supply valve |29 and passage IIB connected via rotary valve 22,2 to exhaust pipe |G. By thus rapidly reducing the pressure .of fluid in chamber 2| of ,motor I spring I8 rapidly moves piston I9 its full travel in the direction of Vsaid chamber to a ^position limited by contact with .shms 21, carrying with it stem 4 3, as previously described, and thereby rapidly positioning lever l4t in its corresponding "Predetermined Throttle position to insure safe operation of the engine .during the emergency.

After ,normal conditions vhave .been established ,in the .fluid pressure .supply system, the engineer may vreturn the selector valve device 5 to Pilots Control position, as shown in the drawing, thereby .rendering the system operable .as before described.

Summary From .the 4above description, it will now 'be apparent that I have provided an improved fluid pressure control apparatus for controlling the speed of airplane engines whereby a first opereter; such as a pilot, lat one station may, under normal conditions of rengine operation, control the speed `of an engine through its full operating range while a second operator, such as an engineer, at another station, may control speed or the engine through a 'lesser or Vernier range.

for making Aminor adjustment of engine speed, and whereby at the pilots discretion, also .under normal conditions of engine operation, the pilot may allow the engineer to take control of the engine through its full operating range for testing, warm-up prior to take-oil, or the like, and fur ther, whereby at the discretion of the engineer,

sli

18 l under emergency conditions of engine operation, the engineer may take over control of the engine through its full operating range from the pilot and return same to the pilot upon reestablishing normal conditions, and still further, whereby under emergency conditions of operation of the fluid pressure supply system the engineer at his discretion may take control of operation of the engine away from the pilot and automatically eiect emergency positioning of the enginefs throttle to insure operation of the engine at a'.

safe speed.

Having now described my invention what I claim as new and desire to secure by Letters Pat.- ent is:

1. In combination, a iluid pressure motor ad justable to assume positions between extreme limits of travel in accordance with variations in pressure of fluid between a certain minimum value and a certain maximum value, said motor comprising means responsive to any reduction in said pressure below said minimum value to positionA said motor intermediate said limi-ts, control valve means voperable to effect said variations, emergency valve means operable to render said control valve means ineffective and to effect said reduction, and means for operating said emergency valve means.

2. In combination, a lluid pressure motor afijustable to assume positions between extreme limits of travel in accordance with variations in pressure of,V fluid between a certain minimum value and a certain maximum value, said motor comprising -means responsive to reduction said pressure below said minimum value to position said motor intermediate'said limits, a fir-st pressure control valve device manually operable from one station to effect said variations, a `second flu-id pressure control valve device manually operable from a second station to effect said variations, an `emergency selector valve dev-ice operable from said second station to one position to render said ii-rst fluid pressure control valve means ineffective and operable to another position Yto render both the lfirst and second ii-uid pressure control valve devices ineffective and -to effect said reduction, and means for operating said emergency selector valve means.

3. In combi-nation, a fluid pressure motor adjustable 'to assume positions between extreme limits of travel in accordance -with variations in vpressure of iiuid between a certain minimum value and a certain maximum value, said motor comprising means responsive to reduction in said pressure below said minimum value to position said motor intermediate said limits, a first iluid `pressure rcont-rol valve device manually operable from one `station to effect said variations, ya rseeond fluid pressure control valve device manually operable -from a second station to effect said variations, iluid pressure limiting mechanism operable ,to limit range of operation of said second iluid .pressure control valve device to less than the range 0i operation of seid Iirst 4fluid pressure control valve device, a ,fluid pressure valve device manually operable from seidliirst .station to control operation of .said ,fluid pressure lirrlitlrlg mechanism, an emergency selector valve .device operable from said .second `station to render .the iirst .and second Iud pressure control valve devices ineifective .and to .effect said reduction, and means for operating said emergency valve means.

4. In combination, a uid pressure motor adjustable to assume positions between extreme limits of travel in accordance with variations in .said pressure below said minimum value to position said motor intermediate said limits, a first Afluid pressure control valve device manually operable from one station to effect said variations,` a second fluid pressure control valve device manually operable from a second station to effect said variations, fluid pressure limiting mechanism opkerable to limit range of operation of said second fluid pressure control valve device to less than Athe range of operation of said rst fluid pressure .control valve device, a fluid pressure valvedevice manually operable from said first station to control operation of said fluid pressure limiting mechanism, and an emergency selector valve device operable from said second station to one position to render said first fluid pressure control valve device ineffective and to another position `to render both the first and second uid pressure control valve devices yineffective and to effect said reduction.

5. In combination, a' fluid pressure motor adjustable between extreme limits of travel in accordance with pressure of fluid in a control chamber between a normal minimum value and a maximum value, said motor comprising means responsive to reduction in said pressure below said normal minimum value to position said motor intermediate said limits, a manuallyoperable self-lapping uid pressure control valve device to effect said variations, said control valve device comprising normally seated supply valve means karranged to cooperate with a supply valve seat to control supply of fluid under pressure from a supply chamber to a delivery chamber connected to said controlchamber and normally seated release valvey means arranged to cooperate witha release valve seat to control release of fluid under pressure from said delivery chamber to a. fluid pressure exhaust passage, an operating lever mechanism arranged to be moved manually to positions between extreme opposite limits of travel of said motor in one direction to dispose said supply valve away from said supplyvalve seat a distance in accordance with degree of saidmovement, and in an opposite direction to dispose said release valve away from said release valve seat a distance in accordance with degree of said movement, a spring, and a diaphragm means subject to action of pressure of uid in, said delivery chamber on one side and to action of said spring and pressure of fluid in avchamber on the opposite side arranged to reseat said supply valve means by deflection in one direction and to reseat said release valve means control pressure of fluid in a delivery chamber by supply and release of fluid under pressure to and from said delivery chamber, a second selflapping fluid pressure control valve device at a second station operable to effect said variations, said second self-lapping uid pressure control valve device being adapted to effect said variations in response to pressure of fluid in said delivery chamber and comprising manually operable means for effecting operation thereof, and a fluid pressure emergency selectory valve device manually operable' from said second station to `one position torender said first self-lapping fluid pressure control valve device ineffective-and to .another position to4 render both the first 'and second iiuid pressure valve devices ineffective and to effect said reduction. 1 7. In combination, a fluid pressure adjustabl gmotor, two fluid `pressure control devices one at each of two' different control stations and each comprising ka lever having a zone of movement, means controlled by movement of, either or both of the levers of said control devices to vary pressure of fluid in said motor, limiting means at one of said stations for limiting movement of the lever of the respective control device to a degree less than the movement of the lever of the other control device and means at the other control station separate from the respective control device for rendering said limiting means either effective or ineffective.

8. In combination, aV fluid pressure motor adjustable to assume positions between extreme limits of'travel in accordance with variations in pressure of fluid between a certain minimum value and a certain maximumpvalue, said motor comprising means responsive to any reduction in said pressure below said minimum value to position said motor intermediate said limits, two

control means, one at each of two control sta- 4 tions, means responsive to operation of either by vmovement in the opposite direction, and a i fluid pressure selector valve device associated Ywith said control valve device manually operable toppen said supply chamber to atmosphere to thereby effect said reduction.

In combination, a iiuid pressure motor 'adone of said control means or to operation of both of said control means at the same time to vary pressure of fluid in said motor between said limits, Vernier means at one of said stations for limiting the degree of control of pressure inV said motor by one of said control means to a degree less than by the other control means, and selector means having l'lrst, second and third positions and comprising means operative on said first and second positions to subject the first named means to pressure of fluidprovided by operation of said control means for controlling said motor and operative in a third position to release fluid under pressure from said first named means, said selector means further comprising means operative on said first position to render said Vernier means effective and in said second position ineffective.

v RANKIN J. BUSH.

REFERENCES CITED The following references are of record in the le of this patent:

Rush Jan. 6, 1948 

